class Solution {
    public boolean searchMatrix(int[][] matrix, int target) {
        // 每次删除1行或1列
        int m = matrix.length, n = matrix[0].length;
        int x = 0, y = n - 1;
        while (x < m && y >= 0){
            if (matrix[x][y] == target){
                return true;
            }
            if (matrix[x][y] > target){
                y--;
            } else {
                x++;
            }
        }
        return false;
    }
}